Upset forging is a metal forming process by which metal stock, typically a length of metal bar, is worked to form an unfinished piece. The length of bar is worked to increase a cross-sectional area of a portion or all of the bar stock. The unfinished work piece is then machined (e.g., turning, grinding and the like) and/or treated (e.g., heat treated) to produce a finished product.
An upsetter is a machine with horizontally moving dies that upset forge the metal stock. The metal stock is heated to between 1750 and 2000° F. and then formed in the upsetter. Typical upsetters implement multiple dies in a multi-pass process. For example, the first few passes gradually work the metal stock to a near complete form and the final pass works the stock into the complete form, providing the unfinished work piece.
Some unfinished work pieces require complex geometries to be formed. Unfortunately, traditional upsetters are unable to form these complex geometries. As a result, such unfinished work pieces are formed using alternative metal forming processes. The alternative metal forming processes are more expensive and have longer cycle times than upset forging.